Apparatus and process for developing electromagnetic energy from tire flexure

ABSTRACT

Mounted within a flexible pneumatic tire is an actuator which is reciprocated radially by the normal distortion of the tire as it moves into ground-engagement, is depressed and then expands to its original position as it moves out of ground-engagement. The periodic engagement and disengagement produces a radially reciprocable movement which is used to operate an electromagnetic generator, and the energy derived from the generator is usable either for operating an electrically operable device, or the signal may be monitored to indicate tire parameter conditions such as heat, inflation pressure and other such conditions. A plurality of actuators are locatable within the tire each of which is radially displaceable by the successive engagement and disengagement of the tire with the ground, and each device is successively operative in relation to the electromagnetic generator.

[ Sept. 1%, 1973 APPARATUS AND PROCESS FOR DEVELOPING ELECTROMAGNETICENERGY FROM TIRE FLEXURE [76] lnventor: Stephen Edward Thomas, 13664Ronnie Way, Saratoga, Calif. 95070 22] Filed: July 2,1971

21 Appl.No.:159,272

[52] US. Cl. 340/58, 200/6123 [51] int. Cl. B60C 23/06 {58] Field ofSearch]. 340/58; ZOO/61.22, ZOO/61.23, 61.25

[ 56] Reterences Cited UNITED STATES PATENTS 1,772,949 8/1930 Jacoby340/58 2,274,557 2/1942 Morgan et al.... 340/58 UX 3,453,590 7/1969Burgess et al.... 340/58 3,568,145 3/1971 Dikoff 340/58 3,593,269 7/1971Richardson 340/58 2,629,086 2/1953 Ainsworth et a1. 340/58 PrimaryExaminer-Alvin H. Waring Attorney-John A. Young [57] ABSTRACT Mountedwithin a flexible pneumatic tire is an actuator which is reciprocatedradially by the normal distortion of the tire as it moves intoground-engagement, is depressed and then expands to its originalposition as it moves out of ground-engagement. The periodic engagementand disengagement produces a radially reciprocable movement which isused to operate an electromagnetic generator, and the energy derivedfrom the generator is usable either for operating an electricallyoperable device, or the signal may be monitored to indicate tireparameter conditions such as heat, inflation pressure and other suchconditions.

A plurality of actuators are locatable within the tire each of which isradially displaceable bythe successive engagement and disengagement ofthe tire with the ground, and each device is successively operative inrelation to the electromagnetic generator.

3 Claims, 11 Drawing Figures PATENTEDSEPI 81m 3,760,351

SHEET 1 OF 2 INVENTOR Z STEPHEN E. THOMAS BY 902/" CL. 740%,

ATTORNEY PAIEIII II E 3.760.351

SHEEI 2 OF 2 IIo LAMP/H4 r OR OTHER USE I18 I20 I22 I24 NI IQ NL r 1% NIIS NI IS L I IIP IIQ OTHER USE I2I I TO LAMP OR OTHER USE I36 I36 I32 II GT 7 I44) |5Q I40) EMITTER I66 BRAKE I66 I66 I I66 '4 EMITTER WEMITTER 'NVENTOR STEPHEN E. THOMAS I46 I42 CL F l (5-: 8 BY a 0 ATTORNEYAPPARATUS AND PROCESS FOR DEVELOPING ELECTROMAGNETIC ENERGY FROM TIREFLEXURE BACKGROUND OF THE INVENTION For many years, the art has soughtan inexpensive and reliable tire monitoring device which will tell theoperator when the tire has reached dangerous operating condition, suchas tire underinflation, tire overinflation, excess tire heating and thelike.

One of the reasons why such devices have not become popular is that theyare either too complex and therefore expensive, or they require a powersource which is unreliable, overly affected by operating conditions andthe like. For example, tire warning devices are available which arepressure responsive and which emit a signal by transmitter, but all toofrequently the signal becomes distorted, lost, and suppressed by comditions which are encountered during normal vehicle usage. Consequently,the monitoring of a tire remains a substantial unsolved problem.

The present invention proposes to solve a number of the outstandingproblems including first of all the' provision of a different-powersource by which tire conditions become self-monitored. As part ofthe'normal tire operation, a portion of the periphery of the tire as itcomes into ground-engagement is depressed into a foot" which iselliptical in outline and represents a radial decrease because of theweight of the vehicle on the ground. As the foot passes out ofengagement with the ground, it returns to its normal position with thenet effect being a slight radial flexure of each segment of the tire asit comes successively into groundengagement and then out ofground-engagement. This tire flexure movement representsan untappedsource of energy, and I intend to be the first to recognize thispotential energy source as a means for generating the power and a signalwhereby the tire itself becomes a source of energy for powering signalgeneration which in turn monitors tire parameters.

The reason why previous tire monitoring devices are both inaccurate andunreliable is that they are battery operated and the battery isadversely affected by environmental conditions and pilfering; in thepresent invention, the emitter has proper shielding and a reliable powersource which is less subject to change in transmitting characteristicsas a function of environment.

As a result, theart of monitoring tire conditions is now possible andhas answered the prior unanswered problems.

' Monitoring a tire is not limited to providing information on tireinflation,tire temperature, etc. Other useful data can be monitored asfor example, the rate of speed of the tire, such information is thencompared with other tires of the vehicle to determine whether thevehicle is skidding and corresponding adjustments then made in brakingeffort at the respective wheels.

From the foregoing, it will be seen that a highly valuable result isachieved by the present invention wherein a self-contained unit isdisposable within a tire in a shielded condition and which can generatepower from a heretofore. untapped'source, namely tire flexure, and willthereby provide a signal which is usable for monitoring tire conditions,such as temperature, inflation, etc., and can furthermore be used todetermine the rate of rotation of the tire so that information is,available for skid control operation.

All of the foregoing is achievable bymeans of a simple device which doesnot have to be externally powered, but which is self-powered,self-contained and is located in such manner as to be subject to minimaldistrubances from outside conditions normally encountered in a varietyof locations.

OBJECTS OF THE INVENTION It is the principal object of the presentinvention to provide a self-contained unit which is powered by normalflexure of a tire and is located within a tire to provide a continuousmonitoring of tire conditions, including inflation, temperature, bearingtemperature, etc.

Another object of the present invention is to provide a device which islocated within a tire and is shielded from outside environmentalconditions so as to provide an emitted signal which is carefullycalibrated to tire conditions and is subject to minimal extraneousdisturbances.

A further object of the present invention is to provide a unit which isdisposed within an automobile tire and utilizes the normal flexure ofthe tire as a power source for generating electrical energy, such energybeing usable for a variety of different purposes, includingillumination, generation of RF or sonic transmitting waves, and allows acentral pickup for signal identification, usable for a variety ofdifferent purposes as for example skid control operation or the like.

An overall object of the present invention is to provide a simple andinexpensive device which requires no external power other than normallyderived from the normal flexure of the tire, and to utilize such energypreviously untapped andignored as an energy source, whereby such derivedenergy is usable for a variety of useful purposes. Related to thisobject is the further object that the described device is locatablewithin a tire so as not to be subject to theft, disturbance in anymanner from outside sources, and is shielded by the tire itself, so anysignal obtained from the device is related almost solely to tireconditions, and is therefore a reliable source of RF or sonictransmission.

Other objects and features of the present invention will become apparentfrom a consideration of the following description which proceeds withreference to the accompanying drawings.

DRAWINGS FIG. 1 is a sectional view of an automotive tire whichincorporates the present invention therein, the actuator being shown ingrounded-engaging position in full line, and the two dotted lineground-engaging are the same actuator when the tire is rotated and 315from ground-engagement, rotating out of the plane of the pa- P FIG. 2 isan enlarged sectional detail view of the actuator which illustrates theactuator in an extended position;

' FIG. 3 is a sectional view taken on line 3-3 of FIG. 2;

FIGS. 4A, 4B, 4C and 4D are progressive views illustrating firstcompression stroke of the actuator effecting rotation of the armature in4A, 4B, 4C, and the elongation during 4D until return to the startingpoint of 4A;

FIGS. 5, 6 and 7 are schematic circuit diagrams illustrating how aplurality of the generators are combinable to produce electrical energy;and

FIG. 8 is a block diagram illustrating how the device is usable as askid control system.

GENERAL DESCRIPTION OF THE INVENTION Referring to FIG. 1, a vehicle tiredesignated generally by reference numeral It has a wheel disc 12 with arim 14 and inflatable tire 16 mounted thereon. Within the tire 16 areone or more circumferentially spaced devices I8, each consisting of aplunger 20 engageable at 22 with the internal surface 24 of tire tread26.

A spring 28 holds the plunger 20 in a normally extended position whereinthe end 22 is in engagement with tire surface 24. The plunger 20 movesreciprocably within a sleeve 30 and spring 28 bears at one end against ashoulder 32 of the fixed sleeve 30, and a shoulder 34 of the plunger 20to urge the plunger 20 in an expanding direction. The plunger 20 carriesa camming pin 38 which enters into one or another of the helical grooves40 constructed within a rotatable follower 42 which is of cylindricalconstruction and is caused to rotate by movement of the camming pin 38longitudinally relatively thereto.

The camming pin 38 is held within an opening 44 by detent 47 whichpermits the pin to move within the opening 44 so that the end 48 iseither within one of the helical grooves 40 or is out of engagementtherewith. An inclinded cam face 50 (FIGS. 2, 48, 4D) on the end 32 ofsleeve 30 cams the pin radially inwardly to the position shown in FIG. 2when the spring 28 fully extends the plunger 20 and plunger movement islimited out- I wardly by engagement of pin end 48 with an annularabutment Slat theend of follower 42. The pin 38 is biased inwardly byinclined cam surface 54 which is formed at the upper end 56 of thefollower 42.

When the follower 42 rotates, it also rotates armature 58 which isconnected to follower 42 by a shaft 60. As the armature 58 rotates, itcuts the lines of force surrounding coil 62 and a series of brushes 64which are loaded by springs 66 against commutator 68 communicateelectrical energy to an electrical circuit for some useful purpose. End74 of shaft 60 is mounted on antifriction bearings 76 as indicated inFIG. 2.

The plunger 20 is caused to move upwardly (FIG. 4A, 4B, 4C) since itsend 22 engages the tire portion 24 which is radially foreshortened asthe tire comes into engagement with the ground and forms an ellipticalfoot, foreshortening the distance from the tread of the tire 16 to itscenter. The sequence of operation is such that, as the device is rotatedwith the tire 16 and a portion of the tire 26 becomes depressed, theplunger 20 is moved upwardly as indicated in FIG. 4A. At the maximumextended stroke of plunger 20,(which is the plunger position just priorto ground engagement) pin 38 is biased fully inwardly by engagement ofits end 78 with the inclined surface 50 on the end 32 (FIG. 2) of sleeve30 so that as the plunger moves upwardly in the direction of the arrow90 (FIG. 4A) with the pin 38 at its inward position asindicated by thearrow 92, upward movement of the plunger, by reason of engagement of end46 of the pin within the helical grooves 40, will impart a turningeffort on the follower 42, effecting a rotational movement thereof,together with the shaft 60 and rotor 58.

The rotation of the rotor 58 relatively to the field 62 will generate inelectromagnetic force communicable through commutator 68, and brushes 64to an electrical circuit for performing useful work. As indicated in 4C,as the plunger reaches its maximum contracted or upward movement, theend 46 of pin 38 is moved in the direction of arrow 96 by engagementwith the inclined surface 54 on follower 42. At this point, the portionof tire engageable with end 22 is moved out of engagement with theground, and the natural flexure of the tire to its normal position willmove the plunger 20 in the opposite direction, in the directionindicated by arrow 100 (FIG. 4C) and pin 38 will be moved relatively tothe follower 42 in the direction of the arrow 100 (FIG. 4B) until theend 38 engages inclined cam surface 50 (FIG. 4A) and is cammed inwardlyin the direction indicated by arrow 92 whereupon end 46 will reengagesurface 50 and prevent further extending movement of the plunger 20under the action of the spring 28 which produces extending movement ofthe plunger.

Within a single tire, there may be one or more of the described devices18 and, as indicated in FIG. 5, the devices can be connected in seriesfor maximum voltage and constant current, with a shunt field coil tocommutator brushes, so that each commutator 68 and field coil 62 areshunt-wound with conductors 110, 112, connecting the shunt connectedfield coil to commutator series connection, to a lamp 114 or other use.

Another manner of connecting the various devices is indicated in FIG. 6,in which permanent magnets 118, 120, 122, 124 are provided with thecommutators connected in series and conductors 119, 121 connected to alamp or other use.

In a still further arrangement, if maximum current is required andconstant voltage, the devices are connected in parallel with theopposite sides of each coil connected respectively to conductors 130,132, as indicated by terminals 134, 136, for each field coil.

Referring next to FIG. 8, devices 18 generate an RF or other signaldesignated by emitters 140, 142, 144 and 146 which are associated witheach of the vehicle wheels and transmit a signal which is a measure ofthe rate of rotation of the associated wheel through an associatedconductor 148 in the direction of the arrow 150 to a comparator 152. Thecomparator distinguishes which of the wheels is rotating at a slowerrelative speed and transmits this signal through conductor 154 to abrake control 156, having hydraulic connections 158, 160, 162 and 164with brakes 166 associated one with each of the wheels of the vehicle.In the event that any one of the wheels associated with the emitter 142is locked, indicating a skid, then brake applying force is relieved sothat the wheel or wheels can resume speed.

Thus, the device 18 can generate a signal which is in accordance notonly with tire conditions but also wheel speed. There is alsocomprehended within the teaching of the present invention, the use of anoutput signal of the device to indicate tire conditions and wheel speed,or a combination of both tire signalling and wheel speed to obtain antiskid control.

OPERATION In operation, device 18 located within the tire 16 is broughtinto the full line position shown in FIG. 1 with each revolution of thetire. When the device 20 is in the full line position of FIG. 1, aportion of the tire tread in contact with the end of plunger 20 becomesradially foreshortened with the tread being deformed into an ellipticalfoot" and causing the plunger to become foreshortened moving in thedirection of the arrows 90, FIGS. 4A and 4B. As the plunger foreshortensagainst the resistance of spring 28, the pin 38 which is biased so thatits end 46 is brought within one of the helical grooves 40 of thefollower 42 and will cause the follower 42 to rotate, such rotationacting through shaft 60 to corrotate rotor 58.

Relative rotation between rotor 58 and field coil 62 will generate anEMF which is transferred through commutator 68 and brushes 64 to anelectrical circuit which is available for energizing a lamp, asignalling device, for generating an RF or audio signal, transmitting asignal to a comparator 152 to indicate wheel speed, acceleration anddeceleration data or a combination 0 these purposes.

When the plunger reaches its maximum extent of contraction (FIG. 4C),the end of pin 38 comes into I contact with surface 54 biasing the pin38 inwardly, and at this point the tire is rotated out of contact withthe ground and the natural flexure of the tire will cause the tread toexpand outwardly, thus permitting the spring 28 to extend the plunger inthe direction of the arrows 100 (FIGS..4C and 4D). The maximum ex.-tension of the plunger is determined by engagement of the end 46 of thepin with the annular stop 50 of the follower 42, the pin being thenmoved inwardly again in the direction of the arrow 92 (FIG. 4A) at theend of the longitudinal extension stroke of the plunger by the spring28. Thus during upward plunger movement the pin engages follower 42 androtates it; during downward plunger movement the pin is out ofengagement with the rotor. i

It thus occurs that torque force is communicated to the rotor 58, eachrotation of the tire. The rotation of the tire occurs frequently enough,and sufficient energy is involved during each revolution of the wheel ortire to produce considerable impulses of input energy from the periodicflexure of the tire. As it comes first into engagement with the ground,the ground-engaging tire section is distorted into a foot" and thenpasses out of engagement with the ground and resumes its circumferentialshape.

The electrical energy derived in the manner described, can beinterpreted and is also sufficient in output for a number of usefulpurposes including the operating of running lights to improve the sidevision of the vehicle, operating an alarm to signal underinflation oroverinflation, or overheating of the tire, and the signal can also bedifferentiated to indicate excessive deceler-- ation or wheel lock,these being meaningful signals in anti skid operation.

More than one device can be operated for each tire, such devices to beconnected in the manner indicated for FIG. 5 as in a shunt field coil,to commutator brushes, and the series connection will provide maximumvoltage and constant. current; or permanent magnets can be used in placeof the field coil and the commutators connected in series as indicatedin FIG. 6, or in an even further embodiment indicated in FIG. 7, thedevices can have parallel connections toobtain maximum current andconstant voltage.

' A signal output is further obtainable from each wheel through anassociated emitter, such emitter information being transferred to acomparator which in turn regulates a brake control to the respectivebrake as indicated in FIG. 8.

Although the present invention has been illustrated and described inconnection with a few selected example embodiments, it will beunderstood that these are illustrative of the invention and are by nomeans restrictive thereof. It is reasonably to be expected that thoseskilled in this art can make numerous revisions and adaptations of theinvention, and it is intended that such revisionsand adaptations will beincludedwithin the scope of the following claims as equivalents of theconverting reciprocable movement of said force transmitting means torotary movement of a portion of said electromagnetic generating meansand thereby to generate useful electrical energy. 5

2. The apparatus in accordance with claim 1 includ

1. Apparatus for generating electrical energy from tire flexurecomprising: force transmitting means disposed within the interior of avehicle tire and having mounting means therebetween whereby said forcetransmitting means is arranged to move circumferentially with said tire,an electromagnetic generating means also disposed within said tire,radially displaceable means movable radially responsively to flexure ofthe tire during rotation thereof, and adapted to move said forcetransmitting means therewith, and means converting reciprocable movementof said force transmitting means to rotary movement of a portion of saidelectromagnetic generating means and thereby to generate usefulelectrical energy.
 2. The apparatus in accordance with claim 1 includinga clutch mechanism between said force transmitting means and saidelectromagnetic generating means whereby displacement of a coil and coreportion thereof is effected only during rotation of the tire.
 3. Theapparatus in accordance with claim 1 including conductor means forcommunicating electrical energy generated from said electromagneticgenerating means to an output including a signalling device, a source ofillumination or the like.